Working method and device for smoothing gearwheels

ABSTRACT

A working method and a device for smoothing gearwheels may be operated cost-effectively and in an environmentally friendly way and enables a simple method sequence and device construction. The device for performing the working method is equipped with at least one smoothing wheel, similar to a gearwheel, that acts radially on a gearwheel to be smoothed and that may be engaged with and disengaged from the wheel to be smoothed. A spray nozzle generates a fine spray mist of lubricant such as oil. The spray mist is sprayable in the form of a minimal quantity of lubrication onto the operating region of the gearwheel to be smoothed and/or onto the smoothing wheel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a working method and a device for smoothing gearwheels. The device has at least one smoothing wheel, similar to a gearwheel, that acts radially on a gearwheel to be smoothed and therefore may be engaged and disengaged. The smoothing wheel is driven via a motor and the gearwheel to be smoothed is kept pressed with a high pressure force and along its axis of rotation oscillating against the smoothing wheel during a main operating step. The smoothing wheel acts radially on the gearwheel to be smoothed and therefore may be engaged and disengaged.

A gearwheel burnishing and honing machine described in U.S. Pat. No. 4,414,780 to Jorgensen (corresponding German patent DE 32 30 860 C2) has a similar basic construction as the present invention for smoothing gearwheels. The gearwheels to be smoothed and the smoothing wheels used are washed with a large quantity of a coolant-lubricant emulsion in order to reduce the production of frictional heat and remove the abraded material.

The use of such a coolant-lubricant emulsion particularly has the disadvantage that the entire device must be sealed on all sides in order to prevent the liquid from escaping or spray water, and the emulsion must be kept in a loop and continuously treated, and the abraded material must be removed and/or filtered out of the emulsion in particular. This treatment is very complex and the filters employed in the process must be disposed of and kept new, which generates very high operating costs, maintenance costs, and unnecessarily great environmental strain overall. Furthermore, the shaft bearings used on the smoothing wheels must be provided with a central lubrication so they are not destroyed over long periods by the coolant and lubricant, which are sometimes aggressive. Even if the gearwheels to be smoothed and the smoothing wheels are only washed with low-viscosity oil, the requirement for treating washing oil is maintained.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a method and a device which overcome the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provide for a working method and a device for smoothing gearwheels, which may be operated significantly more cost-effectively and in a more environmentally friendly way and/or which allow a significantly simpler method sequence and device construction.

With the foregoing and other objects in view there is provided, in accordance with the invention, a working method for smoothing gearwheels. The novel method comprises:

providing a device having at least one smoothing wheel disposed to act radially on a gearwheel to be smoothed and to selectively engage and disengage the gearwheel to be smoothed, the device further having a motor driving the smoothing wheel;

pressing the gearwheel to be smoothed with high pressing force against the smoothing wheel and thereby oscillating the gearwheel along an axis of rotation thereof during a main operating step; and

applying a minimal quantity of lubricant to at least one of the gearwheel to be smoothed and the smoothing wheel.

With the above and other objects in view there is also provided, in accordance with the invention, a device for smoothing gear wheels, i.e., a device for performing the above-outlined method. The device comprises:

at least one smoothing wheel, in the form of a gearwheel, disposed to act radially on a gearwheel to be smoothed and to be engaged therewith and disengaged therefrom;

a spray nozzle configured for generating a fine spray mist of lubricant and disposed to spray the lubricant onto at least one of an operating region of a gearwheel to be smoothed and onto the smoothing wheel; and

a pressure generator communicating with the spray nozzle.

Because the device for smoothing gearwheels, which is equipped with at least one smoothing wheel that acts radially on a gearwheel to be smoothed and therefore may be engaged and disengaged, is provided with a spray nozzle, with which a fine lubricant spray mist, particularly made of oil, is sprayable on the gearwheels, it becomes possible to dispense completely with the use of a coolant-lubricant emulsion. In this way, the construction outlay for the device is significantly reduced, since, for example, water-tight boxes which enclose the device must no longer be positioned around the device and central lubrication of the bearings, which may now be replaced by typical permanently-sealed bearings, may be dispensed with completely. Furthermore, the cleaning of the device is significantly simplified, since it is not always completely wetted by the coolant-lubricant emulsion. Post-processing such as drying of the workpieces is also completely dispensed with.

Further advantageous embodiments of the object of the present invention result from and in combination with the following method and device claims.

Because, in an especially advantageous embodiment of the device, the spray nozzle is pointed directly at the gearwheel to be smoothed, it becomes possible to ensure sufficient lubrication during the smoothing process using an extremely small quantity of sprayed oil, without the smoothing wheels or the gearwheel to be smoothed being negatively influenced hereby. Since the device is purely a smoothing device for gearwheels, in which, for example, scale residues from the heat treatment of the gearwheels are removed, hardly any noticeable material abrasion is to be expected, so that the use of washing oil or other cleaning liquid may be dispensed with completely.

The lubricant is preferably sprayed on a free surface region of the gearwheel to be smoothed when the already rotating smoothing wheel has been engaged load-free with the gearwheel to be smoothed, this advantageously occurring during a complete rotation of the gearwheel to be smoothed, through which complete and sufficient lubrication of the entire operating region of the gearwheel is ensured before beginning the basic operating step by applying the high pressure force. Method sequences in which the lubricant is sprayed one or more times shortly before and/or at the beginning of and/or even during the smoothing process are also conceivable.

According to a further preferred embodiment of the object of the present invention, the smoothing machine is equipped with a device, which generates an air stream, and corresponding air distribution lines to the gearwheel to be smoothed, but particularly only to the smoothing wheels, so that their heating because of frictional heat may be counteracted in a very simple and cost-effective way. Furthermore, the gearwheels to be smoothed, which are continuously replaced, contribute to cooling of the smoothing wheels, which are always fixed on the device. In principle, other gases may also be used here.

An embodiment of the device in which the device that generates the air stream is provided with an assembly that operates according to the Joule-Thompson affect and also has a narrow expansion nozzle, in which the highly compressed air cools down strongly as it passes, values below −30° C. to −50° C. being achieved here, is especially advantageous. Using such an assembly, the occurrence of frictional heat is counteracted in a technically simple but effective way, which also operates quasi-wear-free.

The working method which may be performed using the device essentially corresponds to the known methods for smoothing gearwheels, their typical lubrication and cooling using a coolant-lubrication emulsion or using pure washing oils being replaced by an extremely minimal quantity of lubrication using a lubricant such as oil. This oil is sprayed one time at the beginning or during, but particularly before the beginning of the smoothing process, advantageously directly by one single spray nozzle as a fine spray mist onto the gearwheel to be smoothed, this sprayed oil quantity being sufficiently low that even after multiple hours of operation of the device, no oil sprays or larger contaminations are to be found in the region below the smoothing wheels. The application of the lubricant is preferably performed when the rotating smoothing wheel has been engaged load-free with the gearwheel to be smoothed, particularly using a spray stream lasting long enough that the gearwheel may be wetted over its entire circumference and all tooth flanks with lubricant.

The working method is also extremely environmentally friendly, since the quantities of oil used are very low and no liquids to be recycled arise. Furthermore, the entire device is very well accessible at any time, even in operation, and the operating process is observable, since the device is not permanently quasi-“underwater” and the view is not obstructed by sprayed spray protection walls.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a working method and device for smoothing gearwheels, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective illustration of a device for smoothing gearwheels according to the invention; and

FIG. 2 is a perspective detail, on an enlarged scale, of an operating region of the device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown a device for smoothing gearwheels that includes a machine table 10, on which two mutually parallel guide rails 11 are placed. A frame-shaped carriage 12 for a driven smoothing wheel 5 is disposed on the rails 11, as well as a further carriage 13, inside the carriage 12, for a driven pair of smoothing wheels 5. The carriage 12 is movable on the rails. A pressure cylinder 14 is positioned on the carriage 12 for the driven smoothing wheel 5, which presses the carriage 13 for the driven pair of smoothing wheels 5 in the direction toward the driven smoothing wheel 5. A gearwheel 1 to be smoothed is held in operation clamped as a workpiece under a high radial pressure between the pair of smoothing wheels 5 and the single smoothing wheel 5. The gearwheel 1 to be smoothed is held axially clamped so it is radially movable by a clamping device 16, which is positioned on a C-shaped bracket 17. The latter is in turn attached via a spring assembly 18 and via an eccentric 19 on a holding stand 21 on such a way that it allows vertical oscillation of the gearwheel 1, which is only clamped axially, but is mounted quasi-floating radially, via an eccentric drive 20.

In order to be able to set the device for different sizes of gearwheels 1 to be smoothed and/or different smoothing wheels 5, the entire carriage 13 is movable together with the carriage 12 in relation to a fixed vertical axis of the clamping device 16 on the guide rails 11 via a small positioning cylinder 15.

As shown enlarged in FIG. 2, the operating region of the device for smoothing gearwheels primarily includes three smoothing wheels 5 having fixed or pivotable vertical axes of rotation. A first smoothing wheel 5 is positioned on the carriage 12 and is driven by a motor 22 (cf. FIG. 1). The two other smoothing wheels 5 are positioned in a pair on the inner carriage 13 and may be pressed via the pressure cylinder 14 in the direction toward the driven smoothing wheel 5 in such a way that a gearwheel 1 to be smoothed, which is positioned between them, may be pressed against the smoothing wheels 5 using a force of 150 to 500 kg, for example.

Furthermore, the device is equipped with a spray nozzle 2, which may have enough pressure applied to it via a pressure generator 23, such as a pump, and a supply line 24 that a fine vaporized oil spray mist is sprayable on a free surface region of the gearwheel 1 to be smoothed during a complete rotation of the gearwheel 1 to be smoothed. The lubricant is applied after the rotating gearwheel 5 has been engaged load-free, i.e., still without having a pressure force applied to it, with the gearwheel 1 to be smoothed. The nozzle 2 is positioned via a support block 25 and an angularly adjustable carrier 26 on the carriage 13 in such a way that optimized application of the minimum quantity of lubricant may be performed through a very short pump stroke. The short spray stream may be generated in another way, however, such as through a valve-controlled nozzle.

Furthermore, the air cooler 7, which operates according to the Joule-Thomson effect (adiabatic expansion of gas), is also recognizable in FIG. 2. The air cooler 7 is connected to an air distributor 6 that directs air, strongly cooled down to −50° C., for example, against the smoothing wheels 5 to be cooled through three air distributor lines 4 and cold air nozzles 8. If necessary, more air distributor lines 4 may also be provided, even to the gearwheel 1 to be smoothed. The air is generated by a device 3 that generates an air stream, such as a pump or a compressor positioned below the machine table 10.

This application claims the priority, under 35 U.S.C. § 119, of European patent application No. 04003107.2, filed Feb. 12, 2004; the entire disclosure of the prior application is herewith incorporated by reference. 

1. A working method for smoothing gearwheels, which method comprises: providing a device having at least one smoothing wheel disposed to act radially on a gearwheel to be smoothed and to selectively engage and disengage the gearwheel to be smoothed, the device further having a motor driving the smoothing wheel; pressing the gearwheel to be smoothed with high pressing force against the smoothing wheel and thereby oscillating the gearwheel along an axis of rotation thereof during a main operating step; and applying a minimal quantity of lubricant to at least one of the gearwheel to be smoothed and the smoothing wheel.
 2. The working method according to claim 1, which comprises applying the lubricant after the rotating smoothing wheel has been engaged load-free with the gearwheel to be smoothed.
 3. The working method according to claim 1, which comprises applying the minimal quantity of lubricant through a spray nozzle.
 4. The working method according to claim 3, which comprises spraying the lubricant as a very fine spray mist.
 5. The working method according to claim 1, wherein the applying step comprises spraying the lubricant onto a free surface region of the gearwheel to be smoothed.
 6. The working method according to claim 1, wherein the applying step comprises spraying the lubricant with a short pump stroke of a pressure generator.
 7. The working method according to claim 1, which comprises applying the lubricant on the gearwheel to be smoothed during a complete rotation thereof.
 8. The working method according to claim 1, which comprises cooling at least one of the smoothing wheels and the gearwheel to be smoothed by blowing an air stream thereonto.
 9. The working method according to claim 8, which comprises cooling with an air stream of cooled air.
 10. The working method according to claim 9, which comprises generating the cooled air by first subjecting ambient air to high pressure with a pressure generator and subsequently, utilizing the Joule-Thompson effect, passing the air through a narrow nozzle in an air cooler for cooling the air.
 11. A device for smoothing gear wheels, comprising: at least one smoothing wheel disposed to act radially on a gearwheel to be smoothed and to be engaged therewith and disengaged therefrom; a spray nozzle configured for generating a fine spray mist of lubricant and disposed to spray the lubricant onto at least one of an operating region of a gearwheel to be smoothed and onto said smoothing wheel; and a pressure generator communicating with said spray nozzle.
 12. The device according to claim 11, wherein said smoothing wheel is a gearwheel.
 13. The device according to claim 11, wherein said spray nozzle is pointed toward the gearwheel to be smoothed.
 14. The device according to claim 11, which comprises a device for generating an air stream and distributor lines communicating with said device and leading to said at least one smoothing wheel.
 15. The device according to claim 14, wherein said device for generating the air stream includes an air cooler, utilizing the Joule-Thomson effect, having a narrow expansion nozzle for compressed air for strongly cooling the air stream. 